>IUSCLES OF THE NECK. 313 



Inserted into the cavity in the 

 neck of the condyloid process of 

 the lower jaw ; some of its fibres 

 are inserted into the ligament 

 that connects the movable carti- 

 lage and that process to each 

 other. 



Use. To pull the lower jaw 

 forwards, and to the opposite 

 side ; and to pull the ligament 

 from the joint, that it may not 

 be pinched during these motions : when both external ptery- 

 goid muscles act, the fore teeth of the under jaw are pushed 

 forwards beyond those of the upper jaw. 



The Muscles which appear about the anterior part of the Neck. 

 On the side of the neck are two muscles, or layers. 



1. Musculus Cutaneus, vulgo Platysma Myoides, (see fig. 75,) 



Arises, by a number of slender separate fleshy fibres, from 

 the cellular substance that covers the upper part of the deltoid 

 and pectoral muscles ; in their ascent they all unite to form a 

 thin muscle, which runs obliquely upwards along the side of the 

 neck, adhering to the skin. 



Inserted into the lower jaw, between its angle and the origin 

 of the depressor anguli oris, to which it is firmly connected, and 

 but slightly to the skin that covers the inferior part of the mas- 

 seter muscle and parotid glands. 



Use. To assist the depressor anguli oris, in drawing the skin 

 of the cheek downwards ; and when the mouth is shut, it draws 

 all that part of the skin, to which it is connected, below the 

 lower jaw, upwards. — Some of its fibres are inserted into 

 the angle of the mouth, and are connected with the muscles of 



* The two pterygoid muscles. The zygomatic arch and the greater part of 

 the ramus of the lower jaw have been removed in order to bring these muscles 

 into view. 1. The sphenoid origin of the external pterygoid muscle. 2. Its 

 pteryg<^d origin. 3. The internal pterygoid muscle. 



27 



